power: supply: macsmc: Support macOS 27 SMC firmware

The SMC firmware included in macOS 27 changed the size of BCF0 key from
4 to 1 bytes. This key is used for indicating that battery state is
critically low. In addition, B0RM key has changed endianness.

Reviewed-by: Sven Peter <sven@kernel.org>
Reviewed-by: Joshua Peisach <jpeisach@ubuntu.com>
Reviewed-by: Janne Grunau <j@jannau.net>
Cc: stable@vger.kernel.org
Fixes: 0ebf821cf6c7 ("power: supply: Add macsmc-power driver for Apple Silicon")
Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>
Link: https://patch.msgid.link/20260712-gate-power-v4-1-aa59c6583247@chaosmail.tech
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/supply/macsmc-power.c b/drivers/power/supply/macsmc-power.c
index ced07f71e0a87db0a4ea6039bc3b09195b1a5f45..ef735f86394e4c6131f8a45a068baa41f3ef2f8e 100644 (file)
--- a/drivers/power/supply/macsmc-power.c
+++ b/drivers/power/supply/macsmc-power.c
@@ -86,6 +86,11 @@ struct macsmc_power {
        bool has_ch0i; /* Force discharge (Older firmware) */
        bool has_ch0c; /* Inhibit charge (Older firmware) */
        bool has_chte; /* Inhibit charge (Modern firmware) */
+       /*
+        * Battery critical key is 1 byte and charge key is little endian
+        * (Modern firmware)
+        */
+       bool fw_ge_27;
 
        u8 num_cells;
        int nominal_voltage_mv;
@@ -273,6 +278,20 @@ static int macsmc_battery_get_date(const char *s, int *out)
        return 0;
 }
 
+static int macsmc_battery_read_bcf0(struct macsmc_power *power, u32 *val)
+{
+       u8 tval = 0;
+       int ret;
+
+       if (power->fw_ge_27) {
+               ret = apple_smc_read_u8(power->smc, SMC_KEY(BCF0), &tval);
+               *val = tval;
+               return ret;
+       }
+
+       return apple_smc_read_u32(power->smc, SMC_KEY(BCF0), val);
+}
+
 static int macsmc_battery_get_capacity_level(struct macsmc_power *power)
 {
        bool flag;
@@ -280,7 +299,7 @@ static int macsmc_battery_get_capacity_level(struct macsmc_power *power)
        int ret;
 
        /* Check for emergency shutdown condition */
-       if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val) >= 0 && val)
+       if (macsmc_battery_read_bcf0(power, &val) >= 0 && val)
                return POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
 
        /* Check AC status for whether we could boot in this state */
@@ -303,6 +322,12 @@ static int macsmc_battery_get_capacity_level(struct macsmc_power *power)
                return POWER_SUPPLY_CAPACITY_LEVEL_NORMAL;
 }
 
+static s16 macsmc_swap_b0rm(struct macsmc_power *power, s16 b0rm)
+{
+       /* B0RM was Big Endian, likely pass through from TI gas gauge */
+       return power->fw_ge_27 ? b0rm : (s16)swab16(b0rm);
+}
+
 static int macsmc_battery_get_property(struct power_supply *psy,
                                       enum power_supply_property psp,
                                       union power_supply_propval *val)
@@ -397,8 +422,7 @@ static int macsmc_battery_get_property(struct power_supply *psy,
                break;
        case POWER_SUPPLY_PROP_CHARGE_NOW:
                ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
-               /* B0RM is Big Endian, likely pass through from TI gas gauge */
-               val->intval = (s16)swab16(vu16) * 1000;
+               val->intval = macsmc_swap_b0rm(power, vu16) * 1000;
                break;
        case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
                ret = apple_smc_read_u16(power->smc, SMC_KEY(B0DC), &vu16);
@@ -410,8 +434,7 @@ static int macsmc_battery_get_property(struct power_supply *psy,
                break;
        case POWER_SUPPLY_PROP_ENERGY_NOW:
                ret = apple_smc_read_u16(power->smc, SMC_KEY(B0RM), &vu16);
-               /* B0RM is Big Endian, likely pass through from TI gas gauge */
-               val->intval = (s16)swab16(vu16) * power->nominal_voltage_mv;
+               val->intval = macsmc_swap_b0rm(power, vu16) * power->nominal_voltage_mv;
                break;
        case POWER_SUPPLY_PROP_TEMP:
                ret = apple_smc_read_u16(power->smc, SMC_KEY(B0AT), &vu16);
@@ -577,7 +600,7 @@ static void macsmc_power_critical_work(struct work_struct *wrk)
         * Check if SMC flagged the battery as empty.
         * We trigger a graceful shutdown to let the OS save data.
         */
-       if (apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &bcf0) == 0 && bcf0 != 0) {
+       if (macsmc_battery_read_bcf0(power, &bcf0) == 0 && bcf0 != 0) {
                power->orderly_shutdown_triggered = true;
                dev_crit(power->dev, "Battery critical (empty flag set). Triggering orderly shutdown.\n");
                orderly_poweroff(true);
@@ -616,6 +639,7 @@ static int macsmc_power_probe(struct platform_device *pdev)
        struct device *dev = &pdev->dev;
        struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
        struct power_supply_config psy_cfg = {};
+       struct apple_smc_key_info info;
        struct macsmc_power *power;
        bool has_battery = false;
        bool has_ac_adapter = false;
@@ -714,6 +738,20 @@ static int macsmc_power_probe(struct platform_device *pdev)
                if (apple_smc_key_exists(smc, SMC_KEY(CH0I)))
                        power->has_ch0i = true;
 
+               ret = apple_smc_get_key_info(power->smc, SMC_KEY(BCF0), &info);
+               if (ret) {
+                       dev_err(&pdev->dev, "Failed to determine BCF0 key size\n");
+                       return ret;
+               }
+               if (info.size == 1)
+                       power->fw_ge_27 = true;
+               else if (info.size == 4)
+                       power->fw_ge_27 = false;
+               else {
+                       dev_err(&pdev->dev, "Unexpected BCF0 key size %d\n", info.size);
+                       return -EIO;
+               }
+
                /* Reset "Optimised Battery Charging" flags to default state */
                if (power->has_chte)
                        apple_smc_write_u32(smc, SMC_KEY(CHTE), 0);
@@ -766,7 +804,7 @@ static int macsmc_power_probe(struct platform_device *pdev)
                power->nominal_voltage_mv = MACSMC_NOMINAL_CELL_VOLTAGE_MV * power->num_cells;
 
                /* Enable critical shutdown notifications by reading status once */
-               apple_smc_read_u32(power->smc, SMC_KEY(BCF0), &val32);
+               macsmc_battery_read_bcf0(power, &val32);
 
                psy_cfg.drv_data = power;
                power->batt = devm_power_supply_register(dev, &power->batt_desc, &psy_cfg);